An 87-year-old woman was killed early today by a raging fire that tore through her Manhattan apartment, authorities said.

The three-alarm blaze broke out around 3:27 a.m. inside the victim’s second-floor pad in the 15-story building on West 190th Street, between Cabrini Boulevard and Fort Washington Avenue, in Inwood, fire and police officials said.

The woman, identified by tenants as Helen Theoharis, had suffered severe burns and was discovered deceased in her bedroom, according to police sources.

A neighbor one floor above the victim’s residence alerted the doorman to the smoke wafting through the halls, and the doorman called 911, building tenants said.

Firefighters responded and extinguished the flames by 4 a.m., said an FDNY spokesman.

Theoharis lived alone and was bed-ridden, neighbors said. Her home health attendant had left at the end of her shift last night, leaving Theoharis with a telephone and radio, neighbors added.

Fire marshals are investigating the cause of the deadly inferno, which does not appear to be suspicious, the spokesman added.